Decomposing xml schema documents into subsets

ABSTRACT

According to one embodiment of the present invention, a system decomposes a set of schema files. The system receives a set of schema files and automatically identifies a plurality of root schema files in the set, where a root schema file is determined based on remaining schema files in the set lacking a reference to that schema file. For each root schema file, the system creates a subset of the original set of schema files. The subset contains the root schema file, and at least one subset further includes one or more schema files that provide information for that root schema file. Embodiments of the present invention further include a method and computer program product for decomposing a set of schema files in substantially the same manners described above.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/749,136, entitled “DECOMPOSING XML SCHEMA DOCUMENTS INTO SUBSETS” andfiled Jan. 24, 2013, the disclosure of which is incorporated herein byreference in its entirety.

BACKGROUND

1. Technical Field

Present invention embodiments relate to Extensible Markup Language (XML)schema files, and more specifically, to decomposing a set of XML schemafiles into subsets. Each subset contains a root schema file and zero ormore additional schema files that provide information for that rootschema file, directly or indirectly.

2. Discussion of the Related Art

XML schemas are widely used to define standard document types forstoring and exchanging information. An XML schema specifies types of XMLdocuments (e.g., by constraining the content and attributes of allowedelements). Several languages exist for expressing XML schemas, includingData Type Definitions (DTD) and XML Schema Definitions (XSD).

Industry standards are often distributed as a number of XML schemaspackaged in a single zip file. Some of these standards contain hundredsof XSD and Web Services Description Language (WSDL) schema files. When auser wants to import those schema files into an application and createXML parsing or composing jobs based on the imported schemas, the userhas to discover the interrelationships among the schema files first.Importing the entire zip file often results in a type conflict or in aninvalid schema type due to a type being overwritten. This outcome iscommon to many of the industry standard schemas (e.g., ACORD, IRS Taxschema, etc.).

The current practice of discovering the relationships among schema filesis to use editor tools to find the XML elements “include”, “import”, and“redefine” in the schema files and then determine the relationshipsbetween the schema files manually. This approach is practicable when theXML files are simple and few. However, industry standards can he complexand can contain many XML schema files. Furthermore, a number of industrystandards reuse a qualified name fir different elements representingdifferent structures. Duplicate names in different XSD can lead toinvalid and unusable schema libraries that cannot be used for XML jobdesigns.

BRIEF SUMMARY

According to one embodiment of the present invention, a systemdecomposes a set of schema files. The system receives a set of schemafiles and automatically identifies a plurality of root schema files inthe set, where a root schema file is determined based on remainingschema files in the set lacking a reference to that schema file. Foreach root schema file, the system creates a subset of the original setof schema files. The subset contains the root schema file, and at leastone subset further includes one or more schema files that provideinformation for that root schema file. Embodiments of the presentinvention further include a method and computer program product fordecomposing a set of schema files in substantially the same mannersdescribed above.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

Generally, like reference numerals in the various figures designate likecomponents.

FIG. 1 is a diagrammatic illustration of a computing environment for anembodiment of the present invention.

FIG. 2 is a data flow diagram of decomposition of a set of XML schemafiles into subsets according to an embodiment of the present invention.

FIGS. 3A-3B illustrate an example set of XML schema files contained in azip file.

FIG. 4 is a procedural flow chart illustrating an example manner inwhich a set of XML schema files are decomposed into subsets according toan embodiment of the present invention.

FIG. 5A is a schematic illustration of an example graphical userinterface (GUI) for importing a set of schema documents as a zip fileaccording to an embodiment of the present invention.

FIG. 5B is a schematic illustration of an example GUI for browsingschema libraries created from a set of schema documents according to anembodiment of the present invention.

DETAILED DESCRIPTION

Present invention embodiments pertain to decomposing multiple XML schemafiles into subsets corresponding to root schema files. Each subsetcontains a root schema file and zero or more additional schema filesthat provide information for that root schema file, directly orindirectly. For example, an embodiment of the present invention enablesa user to import a zip file containing an industry standard defined bymultiple XML files. The zip file is broken down into multiple subsetscorresponding to top-level schema files, where a top-level schema file(also called a root schema file) is neither included nor imported by anyof the schema files. Subsets of schema files may share any of the schemafiles other than the root schema files. A library is created for eachsubset. The libraries can be used with an application program to designXML parsing and composing jobs.

One aspect of an embodiment of the present invention is to minimize theuser's manual work in discovering the interrelationships among schemafiles in an industry standard. Another aspect is to separate the schemafiles into meaningful sets. Still another aspect is to import them intoseparate libraries. A further aspect is to avoid showing multiple XMLelements with the same name to users at the same time.

An example computing environment for use with a present inventionembodiment is illustrated in FIG. 1. Specifically, the environmentincludes one or more server systems 10 and one or more client orend-user systems 14. Server systems 10 and client systems 14 may beremote from each other and communicate over a network 12.

Network 12 may be implemented by any number of any suitablecommunications media (e.g., wide area network (WAN), local area network(LAN), Internet, Intranet, etc.). Alternatively, server systems 10 andclient systems 14 may be local to each other, and communicate via anyappropriate local communication medium (e.g., local area network (LAN),hardwire, wireless link, Intranet, etc.).

A server system may include an XML module 16 and a schema repository 18for storing schemas. XML module 16 decomposes a set of XML schema files(e.g., a zip file containing XML schemas defining an industry standard,proprietary standard, ad hoc schema, arbitrary collection of schemadocuments, etc.) into subsets corresponding to top-level schema files.In addition, the XML module creates a separate library in the repositoryfor each subset. The XML module and/or the schema repository may bedistributed across plural server systems. Alternatively, the XML moduleand/or schema repository may reside on a client system 14 or othercomputer system in communication with the client system.

Client systems 14 enable users to load XML schema files (e.g., as a zipfile) into XML module 16. The client systems may present any graphicaluser (e.g., GUI, etc.) (FIGS. 5A-5B) or other interface (e.g., commandline prompts, menu screens, etc.) to receive commands from users;interact with XML module 16, repository 18, and other modules orservices; and display results (e.g., browse schemas, view type andelement information, create jobs to compose or parse XML documents basedon a schema, view features of an XML document conforming to a schema,etc.).

Server systems 10 and client systems 14 may be implemented by anyconventional or other computer systems preferably equipped with adisplay or monitor, a base (e.g., including at least one processor 30,memories 40 and/or internal or external network interface orcommunications devices 35 (e.g., modern, network cards, etc.)), optionalinput devices (e.g., a keyboard, mouse, or other input device), and anycommercially available and custom software (e.g., server/communicationssoftware, XML module software, etc.). The computer systems may includeserver, desktop, laptop, and hand-held devices. In addition, the XMLmodule 16 may include one or more modules or units to perform thevarious functions of present invention embodiments described below(e.g., uncompressing zip files, creating zip files, parsing XML schemafiles, determining hierarchies of schema files (e.g., finding top-levelschema files, finding files included directly or indirectly by a schemafile, etc.), validating schemas, browsing schemas, creating schemalibraries, etc.), may be implemented by any combination of any quantityof software and/or hardware modules or units, and may reside withinmemory 40 of the server and/or client systems for execution by processor30. Repository 18 may he implemented by any conventional or other datastorage system.

A data flow diagram illustrating a manner of decomposing a large numberof XML schema documents (e.g., via server system 10 and/or client system14) according to an embodiment of the present invention is illustratedin FIG. 2. In particular, a zip file 210 contains a set of XML schemafiles 220. Some of the schema files 221) may import or include others,thereby forming one or more directed graphs of files, where each graphcorresponds to a distinct schema. Files belonging to separate graphs mayconflict with one another (e.g., two files may use the same qualifiedname for an element of a different type). The zip file is loaded intoXML module 16 (e.g., via client system 14 or server system 10). The XMLmodule decomposes the schema files into subsets 230 corresponding toseparate graphs. A non-root schema file 220 may belong to more than onefile graph (e.g., if it is included by more than one root schema file),in which case subsets contain separate instances of the common schemafile. The XML module creates (e.g., in schema repository 18) one schemalibrary 240 (sometimes referred to as a contract library) for eachsubset. The XML module and schema library may use any languages,formats, and media to represent or store a schema.

Example contents of a zip file 210 are listed in FIG. 3A. The topdirectory level of the example zip file contains two schema files:ItemA.xsd and ItemB.xsd. In addition, the example zip file contains twosubdirectories: Simple and Complex. Each subdirectory contains a schemafile named identity.xsd. Example contents of the schema files are shownin FIG. 3B. ItemA.xsd includes the identity file from subdirectorySimple, while ItemB.xsd includes the identity file from subdirectoryComplex. Each of the two files named identity.xsd defines an elementnamed “identity.” However, the type of the “identity” element isdifferent in the two files. Specifically, the Simple/identity.xsd filespecifies that the identity element contains one element named “name,”while the Complex/identity.xsd file specifies that the “identity”element contains three elements, named “firstName,” “middleInitial,” and“lastName.” Thus, importing the two identity files together would resultin a type conflict or inconsistency. The XML module separates the filesinto two sets {itemA.xsd and Simple/identity.xsd} and {itemB.xsd andComplex.xsd}, each of which defines a valid schema without a typeconflict.

A manner in which a set of XML schema files is decomposed into subsets(e.g., via server system 10 and/or client system 14) according to anembodiment of the present invention is illustrated in FIG. 4. Initially,the XML module receives a set of XML files (e.g., a set of XML filespackaged in a zip file) at step 410. The XML module unzips or otherwiseunpacks the set as necessary. At step 420, the top-level schema files inthe set are identified. The XML module automatically determines thetop-level schema files (e.g., by making a list of all the schema filesin the set, searching each file for include and import statements, anddropping from the list each file included or imported by another). Foreach top-level schema file, a subset of files is created at step 430.The subset contains the top-level schema file and all of the filesincluded or imported by the top-level file directly or indirectly. Atstep 440, the XML module determines whether the files of the subsetcombined constitute a valid description of a schema. For example, thesubset can be tested for internal consistency of element names andtypes. If the schema files are written in XSD or another schemadescription language that is itself an XML language, the combineddescription can be tested for conformity with the rules of the schemadescription language. Alternatively, the validation at step 440 may bepartial (e.g., checks only for specific inconsistencies) or omitted. Ifthe subset does constitute a valid schema, a separate schema library iscreated for that subset in the repository at step 450. At step 460, theXML module determines whether any top-level files remain to beprocessed. If so, processing returns to step 430 where a new subset iscreated for the next top-level file. Otherwise, the process ends.

As a result, each schema library contains the schema files of a singlesubset (i.e., a single hierarchy of schema files, together defining avalid schema). Each library provides access to the type information forany global type within the library. Since each library corresponds to asingle, valid, top-level schema file, a library does not containduplicate global types of the same name, a situation that is commonwithin the zip files provided for industry standards. Furthermore, thetype information may be displayed (e.g., in a GUI via client system 14)for a user in a type viewer. The type viewer can be used to display theentire type regardless of its original source file and language (e.g.,xsd, wsdl, etc.).

FIGS. 5A and 5B illustrate an example manner in which a user imports aset of XML schema documents as a zip file and browses the resultinglibraries (e.g., via client system 14 and/or server 10) according to anembodiment of the present invention. In particular, FIG. 5A illustratesa GUI for a Schema Library Manager (in the background) and a GUI dialogbox (in the foreground). The Schema Library Manager GUI enables a userto browse contract libraries and view and import resources (e.g., zipfiles containing industry standards schemas, individual schemas, etc.).The Schema Library Manager presents the dialog box to enable a user tobrowse a file system and select a file or files (e.g. a zip file) to beimported into one or more contract libraries (e.g., via XML module 16).FIG. 5B illustrates an example in which four schema libraries 240 havebeen generated from an imported zip file, and the user has selected oneof these, the s1040 library. As a result, the Schema Library Managerlists all of the schema files in the s1040 library and their namespaceUniform Resource Identifiers (URIs).

In addition, a GUI may allow a user to inspect a global type within agiven library. The GUI may show all of the elements and attributeswithin the type. Elements and attributes can be inspected to showdetailed information such as their type, namespace URI of theirqualified name, whether they are optional, etc.

Furthermore, after the schema files are imported, given a sample datafile, the system can highlight aspects of the file (e.g., the topelement, the contract library it belongs to, etc.) that describes thedata. This helps the user to better understand the schema.

An embodiment of the present invention can also be used to generate aset of zip files for any set of XML schema files (e.g., XML schemasdefining an industry standard, proprietary standard, ad hoc schema,arbitrary collection of schema documents, etc.). For each top-levelschema file of the set, the embodiment creates a zip file containing thetop-level schema file plus all the schema files related to the top-levelschema file.

It will be appreciated that the embodiments described above andillustrated in the drawings represent only a few of the many ways ofimplementing embodiments for decomposing a large number of XML schemadocuments into multiple subsets.

The topology or environment of the present invention embodiments mayinclude any number of computer or other processing systems (e.g., clientor end-user systems, server systems, etc.) and web sites, databases,libraries or other repositories arranged in any desired fashion, wherethe present invention embodiments may be applied to any desired type ofcomputing environment (e.g., cloud computing, client-server, networkcomputing, mainframe, stand-alone systems, etc.). The computer or otherprocessing systems employed by the present invention embodiments may beimplemented by any number of any personal or other type of computer orprocessing system (e.g., IBM-compatible, laptop, PDA, mobile devices,etc.), and may include any commercially available operating system andany commercially available or custom software (e.g., XML modulesoftware, repository management software, communications software,server software, etc.). These systems may include any types of monitorsand input devices (e.g., keyboard, mouse, voice recognition, touchscreen, etc.) to enter and/or view information.

It is to be understood that the software (e.g., XML module, clientsoftware, server software, information processing software, etc.) of thepresent invention embodiments may be implemented in any desired computerlanguage and could be developed by one of ordinary skill in the computerarts based on the functional descriptions contained in the specificationand flow charts illustrated in the drawings. Further, any referencesherein of software performing various functions generally refer tocomputer systems or processors performing those functions under softwarecontrol. The computer systems of the present invention embodiments mayalternatively be implemented by any type of hardware and/or otherprocessing circuitry.

The various functions of the computer or other processing systems may bedistributed in any manner among any number of software and/or hardwaremodules or units, processing or computer systems and/or circuitry, wherethe computer or processing systems may be disposed locally or remotelyof each other and communicate via any suitable communications medium(e.g., LAN, WAN, Intranet, Internet, hardwire, modem connection,wireless, etc.). For example, the functions of the present inventionembodiments may he distributed in any manner among the variousend-user/client and server systems, and/or any other intermediaryprocessing devices including third party client/server processingdevices. The software and/or algorithms described above and illustratedin the flow charts may be modified in any manner that accomplishes thefunctions described herein. In addition, the functions in the flowcharts or description may be performed in any order that accomplishes adesired operation.

The software of the present invention embodiments (e.g., XML module,repository management software, etc.) may be available on a computeruseable or recordable medium (e.g., magnetic or optical mediums,magneto-optic mediums, floppy diskettes, CD-ROM, DVD, memory devices,etc.) for use on stand-alone systems or systems connected by a networkor other communications medium.

The communication network may he implemented by any number of any typesof communications network (e.g., LAN, WAN, Internet, Intranet, VPN,etc.). The computer or other processing systems of the present inventionembodiments may include any conventional or other communications devicesto communicate over the network via any conventional or other protocols.The computer or other processing systems may utilize any type ofconnection (e.g., wired, wireless, etc.) for access to the network.Local communication media may be implemented by any suitablecommunication media (e.g., local area network (LAN), hardwire, wirelesslink, Intranet, etc.).

The system may employ any number of any conventional or other libraries,databases, data stores or storage structures (e.g., files, databases,data structures, data or other repositories, etc.) to store information(e.g., industry standards, schemas, business content, metadata, etc.).The database system may be implemented by any number of any conventionalor other databases, data stores or storage structures (e.g., files,databases, data structures, data or other repositories, etc.) to storeinformation (e.g., industry standards, schemas, business content,metadata, etc.). The XML module and/or schema repository may be includedwithin or coupled to the server and/or client systems.

Present invention embodiments may be used to decompose any quantity ofsets of schema files of any type (e.g., XSD files, WSDL files, DTDfiles, SGML schema files, etc.) representing any type of schemas (e.g.,industry standards, proprietary standards, ad hoc schemas, arbitrarycollections of schema documents, etc.). The XML module may receiveand/or create any quantity of sets of XML schema files in any format(e.g., zip files, tar files, tgz files, individual files, etc.).

The present invention embodiments may employ any number of any type ofuser interface (e.g., Graphical User Interface (GUI), command-line,prompt, etc.) for obtaining or providing information (e.g., uploadingthe desired schema files, browsing schemas, etc.), where the interfacemay include any information arranged in any fashion. The interface mayinclude any number of any types of input or actuation mechanisms (e.g.,buttons, icons, fields, boxes, links, etc.) disposed at any locations toenter/display information and initiate desired actions via any suitableinput devices (e.g., mouse, keyboard, etc.). The interface screens mayinclude any suitable actuators (e.g., links, tabs, etc.) to navigatebetween the screens in any fashion.

The present invention embodiments are not limited to the specific tasks,algorithms, or network/environment described above, but may be utilizedfor decomposing any set of XML schema files.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”,“comprising”, “includes”, “including”, “has”, “have”, “having”, “with”and the like, when used in this specification, specify the presence ofstated features, integers, steps, operations, elements, and/orcomponents, but do not preclude the presence or addition of one or moreother features, integers, steps, operations, elements, components,and/or groups thereof.

The corresponding structures, materials, acts, and equivalents of allmeans or step plus function elements in the claims below are intended toinclude any structure, material, or act for performing the function incombination with other claimed elements as specifically claimed. Thedescription of the present invention has been presented for purposes ofillustration and description, but is not intended to be exhaustive orlimited to the invention in the form disclosed. Many modifications andvariations will be apparent to those of ordinary skill in the artwithout departing from the scope and spirit of the invention. Theembodiment was chosen and described in order to best explain theprinciples of the invention and the practical application, and to enableothers of ordinary skill in the art to understand the invention forvarious embodiments with various modifications as are suited to theparticular use contemplated.

As will be appreciated by one skilled in the art, aspects of the presentinvention may be embodied as a system, method or computer programproduct. Accordingly, aspects of the present invention may take the formof an entirely hardware embodiment, an entirely software embodiment(including firmware, resident software, micro-code, etc.) or anembodiment combining software and hardware aspects that may allgenerally be referred to herein as a “circuit,” “module” or “system,”Furthermore, aspects of the present invention may take the form of acomputer program product embodied in one or more computer readablemedium(s) having computer readable program code embodied thereon.

Any combination of one or more computer readable medium(s) may beutilized. The computer readable medium may be a computer readable signalmedium or a computer readable storage medium. A computer readablestorage medium may be, for example, but not limited to, an electronic,magnetic, optical, electromagnetic, infrared, or semiconductor system,apparatus, or device, or any suitable combination of the foregoing. Morespecific examples (a non-exhaustive list) of the computer readablestorage medium would include the following: an electrical connectionhaving one or more wires, a portable computer diskette, a hard disk, arandom access memory (RAM), a read-only memory (ROM), an erasableprogrammable read-only memory (EPROM or Flash memory), an optical fiber,a portable compact disc read-only memory (CD-ROM), an optical storagedevice, a magnetic storage device, or any suitable combination of theforegoing. In the context of this document, a computer readable storagemedium may be any tangible medium that can contain, or store a programfor use by or in connection with an instruction execution system,apparatus, or device.

A computer readable signal medium may include a propagated data signalwith computer readable program code embodied therein, for example, inbaseband or as part of a carrier wave. Such a propagated signal may takeany of a variety of forms, including, but not limited to,electro-magnetic, optical, or any suitable combination thereof. Acomputer readable signal medium may be any computer readable medium thatis not a computer readable storage medium and that can communicate,propagate, or transport a program for use by or in connection with aninstruction execution system, apparatus, or device.

Program code embodied on a computer readable medium may be transmittedusing any appropriate medium, including but not limited to wireless,wireline, optical fiber cable, RF, etc., or any suitable combination ofthe foregoing.

Computer program code for carrying out operations for aspects of thepresent invention may be written in any combination of one or moreprogramming languages, including an object oriented programming languagesuch as Java, Smalltalk, C++ or the like and conventional proceduralprogramming languages, such as the “C” programming language or similarprogramming languages. The program code may execute entirely on theuser's computer, partly on the user's computer, as a stand-alonesoftware package, partly on the user's computer and partly on a remotecomputer or entirely on the remote computer or server. In the latterscenario, the remote computer may be connected to the user's computerthrough any type of network, including a local area network (LAN) or awide area network (WAN), or the connection may be made to an externalcomputer (for example, through the Internet using an Internet ServiceProvider).

Aspects of the present invention are described with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems) and computer program products according to embodiments of theinvention. It will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer program instructions. These computer program instructions maybe provided to a processor of a general purpose computer, specialpurpose computer, or other programmable data processing apparatus toproduce a machine, such that the instructions, which execute via theprocessor of the computer or other programmable data processingapparatus, create means for implementing the functions/acts specified inthe flowchart and/or block diagram block or blocks.

These computer program instructions may also be stored in a computerreadable medium that can direct a computer, other programmable dataprocessing apparatus, or other devices to function in a particularmanner, such that the instructions stored in the computer readablemedium produce an article of manufacture including instructions whichimplement the function/act specified in the flowchart and/or blockdiagram block or blocks.

The computer program instructions may also be loaded onto a computer,other programmable data processing apparatus, or other devices to causea series of operational steps to be performed on the computer, otherprogrammable apparatus or other devices to produce a computerimplemented process such that the instructions which execute on thecomputer or other programmable apparatus provide processes forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks.

The flowchart and block diagrams in the Figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods and computer program products according to variousembodiments of the present invention. In this regard, each block in theflowchart or block diagrams may represent a module, segment, or portionof code, which comprises one or more executable instructions forimplementing the specified logical function(s). It should also be notedthat, in some alternative implementations, the functions noted in theblock may occur out of the order noted in the figures. For example, twoblocks shown in succession may, in fact, be executed substantiallyconcurrently, or the blocks may sometimes be executed in the reverseorder, depending upon the functionality involved. It will also be notedthat each block of the block diagrams and/or flowchart illustration, andcombinations of blocks in the block diagrams and/or flowchartillustration, can be implemented by special purpose hardware-basedsystems that perform the specified functions or acts, or combinations ofspecial purpose hardware and computer instructions.

The various modules (e.g., XML module, repository manager, etc.) may beimplemented by any combination of any quantity of software and/orhardware modules or units, and may reside within memory 40 of the serverand client systems for execution by processor 30.

What is claimed is:
 1. A computer-implemented method of decomposing aset of schema files comprising: automatically identifying a plurality ofroot schema files in the set of schema files, wherein a root schema fileis determined based on remaining schema files in the set lacking areference to that schema file; and creating a subset for each rootschema file, wherein each subset contains the root schema file and atleast one subset further includes one or more schema files that provideinformation for that root schema file.
 2. The computer-implementedmethod of claim 1, wherein creating a subset comprises validating aschema defined by the subset.
 3. The computer-implemented method ofclaim 1, wherein creating a subset comprises creating a library andstoring a schema defined by the subset in the library.
 4. Thecomputer-implemented method of claim 1, wherein the set of schema filesdefines an industry standard.
 5. The computer-implemented method ofclaim 3, further including: displaying a user interface providinginformation pertaining to a type within at least one of the libraries,wherein the information includes elements and attributes of the type. 6.The computer-implemented method of claim 1, wherein the at least oneschema file that provides information for the root schema file of thatsubset provides the information to the root schema file indirectly; andautomatically identifying a plurality of root schema files in the set ofschema files comprises making a list of the schema files in the set ofschema files, searching each file of the set of schema files for includeand import statements, and removing from the list each file included orimported by another file of the set of schema files.
 7. Thecomputer-implemented method of claim 3, further including: displayinginformation pertaining to the sets of schema files and visuallydistinguishing the root schema files and their corresponding libraries.8. The computer implemented method of d aim 1, further comprising:creating for each subset a file containing the schema files of thesubset.